<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
	div {
		width: 200px;
		height: 200px;
		border: 1px solid red;
	}
	div:first-child {
		border-radius: 10px;
	}
	div:nth-child(2) {
		/*border-radius: 100px;*/
		border-radius: 50%;
	}
	div:nth-child(3) {
		border-radius: 20px 40px;
	}
	div:nth-child(4) {
		border-radius: 20px 40px 80px;
	}
	div:nth-child(5) {
		border-radius: 20px 40px 80px 100px;
	}
	div:nth-child(6) {
		border-radius: 100px;
		height: 100px;
	}
	div:nth-child(7) {
		border-radius: 100px 0;
	}
	</style>
</head>
<body>
	<div></div>
	<div></div>
	<div></div>
	<div></div>
	<div></div>
	<div></div>
	<div></div>
	<div></div>
	<div></div>
	<div></div>
</body>
</html>